I believe the usual uninformed thinking is "terraform exists outside of AWS, so I can move off of AWS" versus "we have used CF or Bicep, now we're stuck" kind of deal

Which is to say both of you are correct, but OP was highlighting the improper expectations of "if we write in TF, sure it sucks balls but we can then just pivot to $other_cloud" not realizing it's untrue and now you've used a rusty paintbrush as a screwdriver

I don’t think that expectation exists with anyone with even the slightest understanding of IaC and systems.

But maybe I’ve just been blessed to work with people who aren’t complete idiots?